As an important group of plant cellular organelles, the molecular mechanism of plastid division is poorly understood. Recent studies have revealed that the homologs of ftsZ gene, an essential prokaryotic cell division...As an important group of plant cellular organelles, the molecular mechanism of plastid division is poorly understood. Recent studies have revealed that the homologs of ftsZ gene, an essential prokaryotic cell division gene, are involved in plastid division process of plant cells. Antisense and sense expression constructions were employed to investigate the functions of the two ftsZ genes, NtFtsZ1 and NtFtsZ2, in transgenic Nicotiana tabacum L. plants. Although antisense expression of,NtFtsZs reduced the native protein level obviously, the size and number of chloroplasts in transgenic tobacco plants had no effect. In contrast, overexpression of NtFtsZs in transgenic plants strikingly changed the number and morphology of chloroplasts. Even only 1 - 2 huge chloroplasts could be seen in the mesophyll cells of some overexpression transgenic plants. Analyses of chloroplast ultrastructures and chlorophyll content of different transgenic plants suggested that NtFtsZs gene have no direct influence on the normal development and function of chloroplasts. ne changes in chloroplast morphology must be a compensation for the change in chloroplast number. The different phenotypes of chloroplasts in antisense and sense transgenic plants implied that different members from the same ftsZ gene family may have similar function in controlling plastid division. Meanwhile, the changes of chloroplast morphology in sense transgenic plants represented the possible plastoskeleton function of ftsZ in higher plant.展开更多
The inheritance of plastid DNA in Pharbitis was studied by the method of restriction fragment length polymorphisms (RFLP).Experimental results showed that plastid DNA from Pharbitis was paternally inherited in recipro...The inheritance of plastid DNA in Pharbitis was studied by the method of restriction fragment length polymorphisms (RFLP).Experimental results showed that plastid DNA from Pharbitis was paternally inherited in reciprocal crosses,P. nil ×P. limbata and P. limbata×P. nil hybrids.But,in the cross of P. limbata×P. nil,the possibility of biparental inheritance of plastid DNA could not be roled out in our preliminary experiment.Thus Pharbitis became the third genus among angiosperms characterized with male plastid transmission.The mechanisms of paternal plastids DNA inheritance in Pharbitis is unclear.The authors proposed that dilution,exclusion and/or degeneration of maternal plastid,including their DNA,after fertilization should be considered.展开更多
The inheritance of chloroplast DNA (cpDNA) in sweet potato (Ipomoea batatas Lain.) was analyzed using DNA restriction fingerprinting. The cpDNA fingerprints of hybrids from reciprocal crosses between Xushu18 and AB78-...The inheritance of chloroplast DNA (cpDNA) in sweet potato (Ipomoea batatas Lain.) was analyzed using DNA restriction fingerprinting. The cpDNA fingerprints of hybrids from reciprocal crosses between Xushu18 and AB78-1 were found to be identical to those of their female parents, which reveals that cpDNA of sweet potato is maternally inherited in this intervarietal crossing. This maternal cpDNA transmission pattern does not accord with the putative one based on former cytological studies. The plastid inheritance in Convolvulaceae has been briefly reviewed in this study, and the utility of DNA restriction fingerprinting analysis in the study of plastid inheritance is also discussed.展开更多
Two plastid division genes, NtFtsZ1 and NtFtsZ2 isolated from Nicotiana tabacum L. were fused with gfp and expressed in Escherichia coli . The regular localizations of full length NtFtsZs∶GFP along the fil...Two plastid division genes, NtFtsZ1 and NtFtsZ2 isolated from Nicotiana tabacum L. were fused with gfp and expressed in Escherichia coli . The regular localizations of full length NtFtsZs∶GFP along the filamentous bacteria indicated that the NtFtsZs could recognize the potential division sites in E. coli and be polymerized with heterogeneous FtsZ from bacteria. The overexpression of NtFtsZs ∶ gfp inhibited the division of host strain cells and resulted in the long filamentous bacterial morphology. These results suggested that eukaryotic ftsZs have similar function to their prokaryotic homologs. Meanwhile, the different deletions of motifs of NtFtsZs are also employed to investigate the functions of these proteins in E. coli . The results showed that the C_terminal domains of NtFtsZs were related to the correct localization of NtFtsZs in E. coli and the N_terminal domains of NtFtsZs were responsible for the polymerization of homogeneous and heterogeneous FtsZ proteins. The significance of these results in understanding the functions of NtFtsZs in plastid division were discussed.展开更多
Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuber and tuberous roots, and fleshy fruit development. Based on previously reported ...Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuber and tuberous roots, and fleshy fruit development. Based on previously reported in vitro assays, β amylase is considered as one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was shown often extrachloroplastic in living cells. Recently we have shown for the first time that β_amylase is predominantly immuno_localized to plastids in living cells of developing apple fruit. But it remains to know whether this model of β_amylase compartmentation is more widespread in plant living cells. The present experiment, conducted in tuberous root of sweet potato ( Ipomea batatas Lam. cv. Xushu 18) and via immunogold electron_microscopy technique, showed that β amylase visualized by gold particles was predominantly localized in plastids especially at periphery of starch granules, but the gold particles were scarcely found in other subcellular compartments, indicating that the enzyme is subcellularly compartmented in the same zone as its starch substrates. The density of gold particles (β amylase) in plastids was increasing during growing season, but the predominantly plastid_distributed pattern of β amylase in cells was shown unchanged throughout the tuberous root development. These data prove that the enzyme is compartmented in its functional sites, and so provide evidence to support the possible widespread biological function of the enzyme in catalyzing starch breakdown in plant living cells or at least in living cells of plant storage organs.展开更多
AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of to...AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of tobacco （Nicotiana tabacum cv. SR1）, to investigate the transgene expression and pE2 accumulation in plastids, and to evaluate the antigenic effect of the plastid-derived pE2 in mice. METHODS： Plastid-targeting vector pRB94-E2 containing the E2 fragment driven by rice psbA promoter was constructed. Upon delivery into tobacco plastids, this construct could initiate homologous recombination in psaB-trnfM and trnG-psbC fragments in plastid genome, and result in transgene inserted between the two fragments. The pRB94-E2 was delivered with a biolistic particle bombardment method, and the plastid-transformed plants were obtained following the regeneration of the bombarded leaf tissues on a spectinomycin-supplemented medium. Transplastomic status of the regenerated plants was confirmed by PCR and Southern blot analysis, transgene expression was investigated by Northern blot analysis, and accumulation of pE2 was measured by ELISA. Furthermore, protein extracts were used to immunize mice, and the presence of the pE2-reactive antibodies in serum samples of the immunized mice was studied by ELISA. RESULTS： Transplastomic lines confirmed by PCR and Southern blot analysis could actively transcribe the E2 mRNA. The pE2 polypeptide was accumulated to a level as high as 13.27 μg/g fresh leaves. The pE2 could stimulate the immunized mice to generate pE2-specific antibodies. CONCLUSION： HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.展开更多
The cosmopolitan family Solanaceae,which originated and first diversified in South America,is economically important.The tribe Hyoscyameae is one of the three clades in Solanaceae that occurs outside of the New World;...The cosmopolitan family Solanaceae,which originated and first diversified in South America,is economically important.The tribe Hyoscyameae is one of the three clades in Solanaceae that occurs outside of the New World;Hyoscyameae genera are distributed mainly in Europe and Asia,and have centers of species diversity in the Qinghai-Tibet Plateau and adjacent regions.Although many phylogenetic studies have focused on Solanaceae,the phylogenetic relationships within the tribe Hyoscyameae and its biogeographic history remain obscure.In this study,we reconstructed the phylogeny of Hyoscyameae based on whole chloroplast genome data,and estimated lineage divergence times according to the newly reported fruit fossil from the Eocene Patagonia,Physalis infinemundi,the earliest known fossil of Solanaceae.We reconstructed a robust phylogeny of Hyoscyameae that reveals the berry fruit-type Atropa is sister to the six capsule-bearing genera(Hyoscyameae sensu stricto),Atropanthe is sister to the clade(Scopolia,Physochlaina,Przewalskia),and together they are sister to the robustly supported AnisoduseHyoscyamus clade.The stem age of Hyoscyameae was inferred to be in the Eocene(47.11 Ma,95%HPD:36.75e57.86 Ma),and the crown ages of Hyoscyameae sensu stricto were estimated as the early Miocene(22.52 Ma,95%HPD:15.19e30.53 Ma),which shows a close correlation with the rapid uplift of the Qinghai-Tibet Plateau at the Paleogene/Neogene boundary.Our results provide insights into the phylogenetic relationships and the history of the biogeographic diversification of the tribe Hyoscyameae,as well as plant diversification on the Qinghai-Tibet Plateau.展开更多
The genus Trigonotis comprises nearly 60 species mainly distributed in East and Southeast Asia.China has the largest number of Trigonotis species in the world,with a total of 44 species,of which 38 are endemic.Nutlet ...The genus Trigonotis comprises nearly 60 species mainly distributed in East and Southeast Asia.China has the largest number of Trigonotis species in the world,with a total of 44 species,of which 38 are endemic.Nutlet morphology is useful for the taxonomic delimitation of Trigonotis.However,there are still controversial circumscriptions of nutlet shape in some species.In previous studies,interspecies phylogenetic relationships were inferred using few DNA markers and very few taxa,which possibly led to erroneous or incomplete conclusions.In this study,the nutlet morphology of 39 Trigonotis taxa and the characteristics of 34 complete chloroplast genomes(29 taxa)were investigated and analyzed.Then,the phylogenetic relationships were discussed within this genus based on complete chloroplast genomes.To the best of our knowledge,this study is the first comprehensive analysis of nutlet morphology and complete chloroplast genome of Trigonotis.Based on nutlet morphology,Trigonotis can be divided into two groups:Group 1,hemispherical or oblique tetrahedron with carpopodiums,and Group 2,inverted tetrahedron without carpopodiums.The chloroplast genome of Trigonotis exhibited a typical quadripartite structure,including 84-86 protein-coding,37 transfer RNA,and 8 ribosomal RNA genes,with a total length of 147,247-148,986 bp.Genes in the junctions were well conserved in Trigonotis,similar to those in other Boraginaceae s.str.species.Furthermore,Trigonotis chloroplast genomes showed relatively high diversity,with more conserved genic regions than intergenic regions;in addition,we detected 14 hot spots(Pi>0.005)in non-coding regions.Phylogenetic analyses based on chloroplast genome data identified highly resolved relationships between Trigonotis species.Specifically,Trigonotis was divided into two clades with strong support:one clade included species with hemispherical or oblique tetrahedron nutlets with carpopodiums and bracts,whereas the other clade included species with inverted tetrahedron nutlets without carpopodiums or bracts.Our results may inform future taxonomic,phylogenetic,and evolutionary studies on Boraginaceae.展开更多
Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals.The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mu...Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals.The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mutants,while the physiological role of their residual plastid DNAs remains unclear.In this study,we obtained five bleached mutants by ofloxacin(Ofl)treatment,identified 12 residual plastid genes in five bleached mutants,and determined the mRNA levels in the wild type E.gracilis(WT)and one bleached mutant(OflB2)under dark and light stimulation conditions by quantitative reverse transcribed PCR(qRTPCR).Results show that the expression of all selected plastid genes in both WT and OflB2 mutant did not change significantly in darkness,while their responses to light stimulation were different.Under the light stimulation conditions,half of the genes did not change significantly,while most of the other genes were down-regulated in OflB2 mutant and up-regulated in WT.Therefore,the bleached mutant retains part of the plastid genome and the plastid relic is responsive to light.Our research will help to understand the functions of residual plastid DNA and evolution of chloroplasts.展开更多
Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragment...Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragments of exogenous gene were integrated to construct lettuce plastid expression vector p Brpo AGFP,which harbored the expression cassette Prrn-gfp-aad A-Tpsb A. The results showed that the amplified flanking fragments were 1.2 and 1.1 kb in size. After sequencing,restriction digestion,ligation and transformation,lettuce plastid expression vector containing expression cassette Prrn-gfp-aad A-Tpsb A was constructed and confirmed by SDS-PAGE electrophoresis. The results of SDS-PAGE electrophoresis indicated that gfp gene was efficiently expressed under the regulation of plasmid specific promoter Prrn and terminator Tpsb A. GFP accounted for 45. 6% of total soluble proteins; inclusion bodies accounted for 47.5 % of bacterial proteins,which reached relatively high expression levels. The construction of lettuce plastid expression vector p Brpo A-GFP laid a solid foundation for establishment of subsequent lettuce plastid transformation system and genetic improvement of lettuce using various functional genes.展开更多
The novelty and suitability of the mitochondrial gene CO1 in DNA barcoding as a reliable identification tool in animal species are undisputed. This is attributed to its standardized sequencing segment of the mitochond...The novelty and suitability of the mitochondrial gene CO1 in DNA barcoding as a reliable identification tool in animal species are undisputed. This is attributed to its standardized sequencing segment of the mitochondrial cytochrome c oxidase-1 gene (CO1) which has the necessary universality and variability making it a generally acceptable barcode region. CO1 is a haploid single locus that is uniparentally-inherited. Protein-coding regions are present in high-copy numbers making it an ideal barcode. The mitochondrial oxidase subunit I (COI) gene is a robust barcode with a suitable threshold for delineating animals and is not subject to drastic length variation, frequent mononucleotide repeats or microinversions. However, a low nucleotide substitution rate of plant mitochondrial genome [mtDNA] precludes the use of CO1 as a universal plant DNA barcode and makes the search for alternative barcode regions necessary. Currently, there exists no universal barcode for plants. The plastid region reveals leading candidate loci as appropriate DNA barcodes yet to be explored in biodiversity studies in Kenya. Four of these plastid regions are portions of coding genes (matK, rbcL, rpoB, and rpoC1), and three noncoding spacers (atpF-atpH, trnH-psbA, and psbK-psbL) which emerge as ideal candidate DNA loci. While different research groups propose various combinations of these loci, there exists no consensus;the lack thereof impedes progress in getting a suitable universal DNA barcode. Little research has attempted to investigate and document the applicability and extend of effectiveness of different DNA regions as barcodes to delineate cowpea at subspecies level. In this study we sought to test feasibility of the seven putative candidate DNA loci singly and in combination in order to establish a suitable single and multi-locus barcode regions that can have universal application in delineating diverse phylogeographic groups of closely related Kenyan cowpea variants. In this study, our focus was based on genetic parameters including analyses of intra- and infra-specific genetic divergence based on intra- and infra-specific K2P distances;calculation of Wilcoxon signed rank tests of intra-specific divergence among loci and coalescence analyses to delineate independent genetic clusters. Knowledge of DNA candidate loci that are informative will reveal the suitability of DNA barcoding as a tool in biodiversity studies. Results of this study indicate that: matK, trnH-psbA, psbK-psbL, and rbcL are good barcodes for delineating intra and infraspecific distances at single loci level. However, among the combinations, matK + trnH-psbA, rpoB + atpF-atpH + matK are the best barcodes in delineating cowpea subvariants. rbcL gene can be a suitable barcode marker at single locus level, but overall, multi locus approach appears more informative than single locus approach. The present study hopes to immensely contribute to the scanty body of knowledge on the novelty of DNA barcoding in cataloguing closely related cowpea variants at molecular level and hopes to open up future research on genomics and the possibility of use of conserved regions within DNA in inferring phylogenetic relationships among Kenyan cowpea variants.展开更多
The expression of double-stranded RNAs(dsRNAs)from the plastid genome has been proven to be an effective method for controlling herbivorous pests by targeting essential insect genes.However,there are limitations to th...The expression of double-stranded RNAs(dsRNAs)from the plastid genome has been proven to be an effective method for controlling herbivorous pests by targeting essential insect genes.However,there are limitations to the efficiency of plastid-mediated RNA interference(PM-RNAi)due to the initial damage caused by the insects and their slow response to RNA interference.In this study,we developed transplastomic poplar plants that express dsRNAs targeting the b-Actin(dsACT)and Srp54k(dsSRP54K)genes of Plagiodera versicolora.Feeding experiments showed that transplastomic poplar plants can cause significantly higher mortality in P.versicolora larvae compared with nuclear transgenic or wild-type poplar plants.The efficient killing effect of PM-RNAi on P.versicolora larvae was found to be dependent on the presence of gut bacteria.Importantly,foliar application of a gut bacterial strain,Pseudomonas putida,will induce dysbiosis in the gut bacteria of P.versicolora larvae,leading to a significant acceleration in the speed of killing by PM-RNAi.Overall,our findings suggest that interfering with gut bacteria could be a promising strategy to enhance the effectiveness of PM-RNAi for insect pest control,offering a novel and effective approach for crop protection based on RNAi technology.展开更多
Mechanisms that allocate cellular space to organelles are of fundamental importance to biology but remain poorly understood.A detailed understanding of mechanisms that allocate cellular space to plastids,such as chlor...Mechanisms that allocate cellular space to organelles are of fundamental importance to biology but remain poorly understood.A detailed understanding of mechanisms that allocate cellular space to plastids,such as chloroplasts,will lead to high-yielding crops with enhanced nutritional value.The HIGH PIGMENT(HP)genes in tomato contribute to regulated proteolysis and abscisic acid metabolism.The HP1 gene was the first gene reported to influence the amount of cellular space occupied by chloroplasts and chromoplasts almost 20 years ago.Recently,our knowledge of mechanisms that allocate cellular space to plastids was enhanced by new information on the influence of cell type on the amount of cellular space occupied by plastids and the identification of new genes that help to allocate cellular space to plastids.These genes encode proteins with unknown and diverse biochemical functions.Several transcription factors were recently reported to regulate the numbers and sizes of chloroplasts in fleshy fruit.If these transcription factors do not induce compensating effects on cell size,they should affect the amount of cellular space occupied by plastids.Although we can now propose more detailed models for the network that allocates cellular space to plastids,many gaps remain in our knowledge of this network and the genes targeted by this network.Nonetheless,these recent breakthroughs provide optimism for future progress in this field.展开更多
The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is inco...The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is incomplete,and phylogenetic relationships within the order Nymphaeales remain controversial.In this study,12 chloroplast genomes of Nymphaea were assembled and analyzed for the first time.These genomes were 158,290-160,042 bp in size and contained 113 non-repeat genes,including 79 protein-coding genes,30 tRNA genes,and four rRNA genes.We also report on codon usage,RNA editing sites,microsatellite structures,and new repetitive sequences in this genus.Comparative genomics revealed that expansion and contraction of IR regions can lead to changes in the gene numbers.Additionally,it was observed that the highly variable regions of the chloroplast genome were mainly located in intergenic regions.Furthermore,the phylogenetic tree showed the order Nymphaeales was divided into three families,and the genus Nymphaea can be divided into five(or three)subgenera,with the subgenus Nymphaea being the oldest.The divergence times of nymphaealean taxa were analyzed,with origins of the order Nymphaeales and family Nymphaeaceae being about 194 and 131 million years,respectively.The results of the phylo-genetic analysis and estimated divergence times will be useful for future evolutionary studies of basal angiosperm lineages.展开更多
Chloroplasts （plastids） possess a genome and their own machinery to express it. Translation in plastids occurs on bacterial-type 70S ribosomes utilizing a set of tRNAs that is entirely encoded in the plastid genome....Chloroplasts （plastids） possess a genome and their own machinery to express it. Translation in plastids occurs on bacterial-type 70S ribosomes utilizing a set of tRNAs that is entirely encoded in the plastid genome. In recent years, the components of the chloroplast translational apparatus have been intensely studied by proteomic approaches and by reverse genetics in the model systems tobacco （plastid-encoded components） and Arabidopsis （nucleus-encoded components）. This work has provided important new insights into the structure, function, and biogenesis of chloroplast ribosomes, and also has shed fresh light on the molecular mechanisms of the translation process in plastids. In addition, mutants affected in plastid translation have yielded strong genetic evidence for chloroplast genes and gene products influencing plant develop- ment at various levels, presumably via retrograde signaling pathway（s）. In this review, we describe recent progress with the functional analysis of components of the chloroplast translational machinery and discuss the currently available evidence that supports a significant impact of plastid translational activity on plant anatomy and morphology.展开更多
Plastid-to-nucleus retrograde signaling coordinates nuclear gene expression with chloroplast developmental status and is essential for the photoautotrophic lifestyle of plants.Previous studies have established that te...Plastid-to-nucleus retrograde signaling coordinates nuclear gene expression with chloroplast developmental status and is essential for the photoautotrophic lifestyle of plants.Previous studies have established that tetrapyrrole biosynthesis(TPB)and plastid gene expression(PGE)play essential roles in plastid retrograde signaling during early chloroplast biogenesis;however,their functional relationship remains unknown.In this study,we generated a series of rice TPB-related gun(genome uncoupled)mutants and systematically analyzed their effects on nuclear and plastid gene expression under normal conditions or when subjected to treatments with norflurazon(NF;a noncompetitive inhibitor of carotenoid biosynthesis)and/or lincomycin(Lin;a specific inhibitor of plastid translation).We show that under NF treatment,expression of plastid-encoded polymerase(PEP)-transcribed genes is significantly reduced in the wild type but is derepressed in the TPB-related gun mutants.We further demonstrate that the derepressed expression of PEPtranscribed genes may be caused by increased expression of the PEP core subunit and nuclear-encoded sigma factors and by elevated copy numbers of plastid genome per haploid genome.In addition,we show that expression of photosynthesis-associated nuclear genes(PhANGs)and PEP-transcribed genes is correlated in the rice TPB-related gun mutants,with or without NF or Lin treatment.A similar correlation between PhANGs and PGE is also observed in the Arabidopsis gun4 and gun5 mutants.Moreover,we show that increased expression of PEP-transcribed plastid genes is necessary for the gun phenotype in NF-treated TPB-related gun mutants.Further,we provide evidence that these TPB-related GUN genes act upstream of GUN1 in the regulation of retrograde signaling.Taken together,our results suggest that the TPB-related GUN genes control retrograde plastid signaling by regulating the PGE-dependent retrograde signaling pathway.展开更多
Arabidopsis plastid antiporters KEA1 and KEA2are critical for plastid development, photosynthetic efficiency, and plant development.Here, we show that KEA1 and KEA2 are involved in vacuolar protein trafficking. Geneti...Arabidopsis plastid antiporters KEA1 and KEA2are critical for plastid development, photosynthetic efficiency, and plant development.Here, we show that KEA1 and KEA2 are involved in vacuolar protein trafficking. Genetic analyses found that the kea1 kea2 mutants had short siliques, small seeds, and short seedlings. Molecular and biochemical assays showed that seed storage proteins were missorted out of the cell and the precursor proteins were accumulated in kea1 kea2. Protein storage vacuoles(PSVs) were smaller in kea1 kea2. Further analyses showed that endosomal trafficking in kea1 kea2 was compromised. Vacuolar sorting receptor 1(VSR1) subcellular localizations, VSR–cargo interactions, and p24 distribution on the endoplasmic reticulum(ER) and Golgi apparatus were affected in kea1 kea2. Moreover, plastid stromule growth was reduced and plastid association with the endomembrane compartments was disrupted in kea1 kea2. Stromule growth was regulated by the cellular pH and K+homeostasis maintained by KEA1 and KEA2. The organellar pH along the trafficking pathway was altered in kea1 kea2. Overall, KEA1 and KEA2 regulate vacuolar trafficking by controlling the function of plastid stromules via adjusting pH and K+homeostasis.展开更多
Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplas...Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. These plastids have dramatic differences in their capacity to synthesize and sequester carotenoids. Clearly, plastids play a central role in governing carotenogenic activity, carotenoid stability, and pigment diversity. Understanding of carotenoid metabolism and accumulation in various plastids expands our view on the multifaceted regulation of carotenogenesis and facilitates our efforts toward developing nutrient-enriched food crops. In this review, we provide a comprehensive overview of the impact of various types of plastids on carotenoid biosynthesis and accumulation, and discuss recent advances in our understanding of the regulatory control of carotenogenesis and metabolic engineering of carotenoids in light of plastid types in plants.展开更多
FtsZ1 and FtsZ2 are phylogenetically distinct families of FtsZ in plants that co-localize to mid-plastid rings and facilitate division of chloroplasts. In plants, altered levels of either FtsZ1 or FtsZ2 cause dose-dep...FtsZ1 and FtsZ2 are phylogenetically distinct families of FtsZ in plants that co-localize to mid-plastid rings and facilitate division of chloroplasts. In plants, altered levels of either FtsZ1 or FtsZ2 cause dose-dependent defects in chloroplast division; thus, studies on the functional relationship between FtsZgenes require careful manipulation of FtsZ levels in vivo. To define the functional relationship between the two FtsZ2 genes in Arabidopsis thaliana, FtsZ2-1 and FtsZ2-2, we expressed FtsZ2-1 in an ftsZ2-2 null mutant, and vice versa, and determined whether the chloroplast division defects were rescued in plants expressing different total levels of FtsZ2. Full rescue was observed when either the FtsZ2-1 or FtsZ2-2 level approximated total FtsZ2 levels in wild-type （WT）. Additionally, FtsZ2-2 interacts with ARC6, as shown previously for FtsZ2- 1. These data indicate that FtsZ2-1 and FtsZ2-2 are functionally redundant for chloroplast division in Arabidopsis. To rigorously validate the requirement of each FtsZ family for chloroplast division, we replaced FtsZ1 with FtsZ2 in vivo, and vice versa, while maintaining the FtsZ level in the transgenic plants equal to that of the total level in WT. Chloroplast division defects were not rescued, demonstrating conclusively that FtsZ1 and FtsZ2 are non-redundant for maintenance of WT chloroplast numbers. Finally, we generated ftsZtriple null mutants and show that plants completely devoid of FtsZ protein are viable and fertile. As plastids are presumably essential organelles, these findings suggest that an FtsZ-independent mode of plastid partitioning may occur in higher plants.展开更多
Phosphoribulokinase （PRK）, a nuclear-encoded plastid-localized enzyme unique to the photosynthetic carbon reduction （Calvin） cycle, was cloned and characterized from the stramenopile alga Vaucheria litorea. This a...Phosphoribulokinase （PRK）, a nuclear-encoded plastid-localized enzyme unique to the photosynthetic carbon reduction （Calvin） cycle, was cloned and characterized from the stramenopile alga Vaucheria litorea. This alga is the source of plastids for the mollusc （sea slug） Elysia chlorotica which enable the animal to survive for months solely by photoautotrophic CO2 fixation. The 1633-bp V. litorea prk gene was cloned and the coding region, found to be interrupted by four introns, encodes a 405-amino acid protein. This protein contains the typical bipartite target sequence expected of nuclearencoded proteins that are directed to complex （i.e. four membrane-bound） algal plastids. De novo synthesis of PRK and enzyme activity were detected in E. chlorotica in spite of having been starved of V. litorea for several months. Unlike the algal enzyme, PRK in the sea slug did not exhibit redox regulation. Two copies of partial PRK-encoding genes were isolated from both sea slug and aposymbiotic sea slug egg DNA using PCR. Each copy contains the nucleotide region spanning exon 1 and part of exon 2 of V litorea prk, including the bipartite targeting peptide. However, the larger prk fragment also includes intron 1. The exon and intron sequences of prk in E. chlorotica and V/itorea are nearly identical. These data suggest that PRK is differentially regulated in V. litorea and E. chlorotica and at least a portion of the V. litorea nuclear PRK gene is present in sea slugs that have been starved for several months.展开更多
文摘As an important group of plant cellular organelles, the molecular mechanism of plastid division is poorly understood. Recent studies have revealed that the homologs of ftsZ gene, an essential prokaryotic cell division gene, are involved in plastid division process of plant cells. Antisense and sense expression constructions were employed to investigate the functions of the two ftsZ genes, NtFtsZ1 and NtFtsZ2, in transgenic Nicotiana tabacum L. plants. Although antisense expression of,NtFtsZs reduced the native protein level obviously, the size and number of chloroplasts in transgenic tobacco plants had no effect. In contrast, overexpression of NtFtsZs in transgenic plants strikingly changed the number and morphology of chloroplasts. Even only 1 - 2 huge chloroplasts could be seen in the mesophyll cells of some overexpression transgenic plants. Analyses of chloroplast ultrastructures and chlorophyll content of different transgenic plants suggested that NtFtsZs gene have no direct influence on the normal development and function of chloroplasts. ne changes in chloroplast morphology must be a compensation for the change in chloroplast number. The different phenotypes of chloroplasts in antisense and sense transgenic plants implied that different members from the same ftsZ gene family may have similar function in controlling plastid division. Meanwhile, the changes of chloroplast morphology in sense transgenic plants represented the possible plastoskeleton function of ftsZ in higher plant.
文摘The inheritance of plastid DNA in Pharbitis was studied by the method of restriction fragment length polymorphisms (RFLP).Experimental results showed that plastid DNA from Pharbitis was paternally inherited in reciprocal crosses,P. nil ×P. limbata and P. limbata×P. nil hybrids.But,in the cross of P. limbata×P. nil,the possibility of biparental inheritance of plastid DNA could not be roled out in our preliminary experiment.Thus Pharbitis became the third genus among angiosperms characterized with male plastid transmission.The mechanisms of paternal plastids DNA inheritance in Pharbitis is unclear.The authors proposed that dilution,exclusion and/or degeneration of maternal plastid,including their DNA,after fertilization should be considered.
文摘The inheritance of chloroplast DNA (cpDNA) in sweet potato (Ipomoea batatas Lain.) was analyzed using DNA restriction fingerprinting. The cpDNA fingerprints of hybrids from reciprocal crosses between Xushu18 and AB78-1 were found to be identical to those of their female parents, which reveals that cpDNA of sweet potato is maternally inherited in this intervarietal crossing. This maternal cpDNA transmission pattern does not accord with the putative one based on former cytological studies. The plastid inheritance in Convolvulaceae has been briefly reviewed in this study, and the utility of DNA restriction fingerprinting analysis in the study of plastid inheritance is also discussed.
文摘Two plastid division genes, NtFtsZ1 and NtFtsZ2 isolated from Nicotiana tabacum L. were fused with gfp and expressed in Escherichia coli . The regular localizations of full length NtFtsZs∶GFP along the filamentous bacteria indicated that the NtFtsZs could recognize the potential division sites in E. coli and be polymerized with heterogeneous FtsZ from bacteria. The overexpression of NtFtsZs ∶ gfp inhibited the division of host strain cells and resulted in the long filamentous bacterial morphology. These results suggested that eukaryotic ftsZs have similar function to their prokaryotic homologs. Meanwhile, the different deletions of motifs of NtFtsZs are also employed to investigate the functions of these proteins in E. coli . The results showed that the C_terminal domains of NtFtsZs were related to the correct localization of NtFtsZs in E. coli and the N_terminal domains of NtFtsZs were responsible for the polymerization of homogeneous and heterogeneous FtsZ proteins. The significance of these results in understanding the functions of NtFtsZs in plastid division were discussed.
文摘Starch degradation in cells is closely associated with cereal seed germination, photosynthesis in leaves, carbohydrate storage in tuber and tuberous roots, and fleshy fruit development. Based on previously reported in vitro assays, β amylase is considered as one of the key enzymes catalyzing starch breakdown, but up to date its role in starch breakdown in living cells remains unclear because the enzyme was shown often extrachloroplastic in living cells. Recently we have shown for the first time that β_amylase is predominantly immuno_localized to plastids in living cells of developing apple fruit. But it remains to know whether this model of β_amylase compartmentation is more widespread in plant living cells. The present experiment, conducted in tuberous root of sweet potato ( Ipomea batatas Lam. cv. Xushu 18) and via immunogold electron_microscopy technique, showed that β amylase visualized by gold particles was predominantly localized in plastids especially at periphery of starch granules, but the gold particles were scarcely found in other subcellular compartments, indicating that the enzyme is subcellularly compartmented in the same zone as its starch substrates. The density of gold particles (β amylase) in plastids was increasing during growing season, but the predominantly plastid_distributed pattern of β amylase in cells was shown unchanged throughout the tuberous root development. These data prove that the enzyme is compartmented in its functional sites, and so provide evidence to support the possible widespread biological function of the enzyme in catalyzing starch breakdown in plant living cells or at least in living cells of plant storage organs.
基金Supported by a grant from the Hong Kong Research Grant Council, No. 7342/03M to YX Zhou and E Lam
文摘AIM： To cost-effectively express the 23-ku pE2, the most promising subunit vaccine encoded by the E2 fragment comprising of the 3＇-portion of hepatitis E virus （HEV） open reading frame 2 （ORF2） in plastids of tobacco （Nicotiana tabacum cv. SR1）, to investigate the transgene expression and pE2 accumulation in plastids, and to evaluate the antigenic effect of the plastid-derived pE2 in mice. METHODS： Plastid-targeting vector pRB94-E2 containing the E2 fragment driven by rice psbA promoter was constructed. Upon delivery into tobacco plastids, this construct could initiate homologous recombination in psaB-trnfM and trnG-psbC fragments in plastid genome, and result in transgene inserted between the two fragments. The pRB94-E2 was delivered with a biolistic particle bombardment method, and the plastid-transformed plants were obtained following the regeneration of the bombarded leaf tissues on a spectinomycin-supplemented medium. Transplastomic status of the regenerated plants was confirmed by PCR and Southern blot analysis, transgene expression was investigated by Northern blot analysis, and accumulation of pE2 was measured by ELISA. Furthermore, protein extracts were used to immunize mice, and the presence of the pE2-reactive antibodies in serum samples of the immunized mice was studied by ELISA. RESULTS： Transplastomic lines confirmed by PCR and Southern blot analysis could actively transcribe the E2 mRNA. The pE2 polypeptide was accumulated to a level as high as 13.27 μg/g fresh leaves. The pE2 could stimulate the immunized mice to generate pE2-specific antibodies. CONCLUSION： HEV-E2 fragment can be inserted into the plastid genome and the recombinant pE2 antigen derived is antigenic in mice. Hence, plastids may be a novel source for cost-effective production of HEV vaccines.
基金We thank Dr.Xiao-Feng Chi and Dr.Ofelia Vargas-Ponce for contributing the whole chloroplast genome sequences of Anisodus tanguticus(Maxim.)Pascher and Physalis philadelphica Lam.before the release in NCBI.This work was supported by the Beijing Natural Science Foundation(Grant No.5192012)National Natural Science Foundation of China(grant number 32070235)the China Scholarship Council(Grant No.201906515009)。
文摘The cosmopolitan family Solanaceae,which originated and first diversified in South America,is economically important.The tribe Hyoscyameae is one of the three clades in Solanaceae that occurs outside of the New World;Hyoscyameae genera are distributed mainly in Europe and Asia,and have centers of species diversity in the Qinghai-Tibet Plateau and adjacent regions.Although many phylogenetic studies have focused on Solanaceae,the phylogenetic relationships within the tribe Hyoscyameae and its biogeographic history remain obscure.In this study,we reconstructed the phylogeny of Hyoscyameae based on whole chloroplast genome data,and estimated lineage divergence times according to the newly reported fruit fossil from the Eocene Patagonia,Physalis infinemundi,the earliest known fossil of Solanaceae.We reconstructed a robust phylogeny of Hyoscyameae that reveals the berry fruit-type Atropa is sister to the six capsule-bearing genera(Hyoscyameae sensu stricto),Atropanthe is sister to the clade(Scopolia,Physochlaina,Przewalskia),and together they are sister to the robustly supported AnisoduseHyoscyamus clade.The stem age of Hyoscyameae was inferred to be in the Eocene(47.11 Ma,95%HPD:36.75e57.86 Ma),and the crown ages of Hyoscyameae sensu stricto were estimated as the early Miocene(22.52 Ma,95%HPD:15.19e30.53 Ma),which shows a close correlation with the rapid uplift of the Qinghai-Tibet Plateau at the Paleogene/Neogene boundary.Our results provide insights into the phylogenetic relationships and the history of the biogeographic diversification of the tribe Hyoscyameae,as well as plant diversification on the Qinghai-Tibet Plateau.
基金This project was funded by the Science and Technology Basic Work,Ministry of Science and Technology,China(2013FY112100 to Q.L.)National Natural Science Foundation of China(31700175 to Z.W.)Fostering Project for Young Teachers of Zhengzhou University,China(JC21343014 to Z.W.).
文摘The genus Trigonotis comprises nearly 60 species mainly distributed in East and Southeast Asia.China has the largest number of Trigonotis species in the world,with a total of 44 species,of which 38 are endemic.Nutlet morphology is useful for the taxonomic delimitation of Trigonotis.However,there are still controversial circumscriptions of nutlet shape in some species.In previous studies,interspecies phylogenetic relationships were inferred using few DNA markers and very few taxa,which possibly led to erroneous or incomplete conclusions.In this study,the nutlet morphology of 39 Trigonotis taxa and the characteristics of 34 complete chloroplast genomes(29 taxa)were investigated and analyzed.Then,the phylogenetic relationships were discussed within this genus based on complete chloroplast genomes.To the best of our knowledge,this study is the first comprehensive analysis of nutlet morphology and complete chloroplast genome of Trigonotis.Based on nutlet morphology,Trigonotis can be divided into two groups:Group 1,hemispherical or oblique tetrahedron with carpopodiums,and Group 2,inverted tetrahedron without carpopodiums.The chloroplast genome of Trigonotis exhibited a typical quadripartite structure,including 84-86 protein-coding,37 transfer RNA,and 8 ribosomal RNA genes,with a total length of 147,247-148,986 bp.Genes in the junctions were well conserved in Trigonotis,similar to those in other Boraginaceae s.str.species.Furthermore,Trigonotis chloroplast genomes showed relatively high diversity,with more conserved genic regions than intergenic regions;in addition,we detected 14 hot spots(Pi>0.005)in non-coding regions.Phylogenetic analyses based on chloroplast genome data identified highly resolved relationships between Trigonotis species.Specifically,Trigonotis was divided into two clades with strong support:one clade included species with hemispherical or oblique tetrahedron nutlets with carpopodiums and bracts,whereas the other clade included species with inverted tetrahedron nutlets without carpopodiums or bracts.Our results may inform future taxonomic,phylogenetic,and evolutionary studies on Boraginaceae.
基金Supported by the National Natural Science Foundation of China(No.31670116)the Guangdong Innovation Research Team Fund(No.2014ZT05S078)the Shenzhen Grant Plan for Science&Technology(Nos.JCYJ20160308095910917,JCYJ20170818100339597,JCYJ 20130329114940668)。
文摘Euglena gracilis is a unicellular green eukaryotic microalga that features characteristics of both plants and animals.The photosynthetic function of its chloroplast is easily lost under stress resulting in bleached mutants,while the physiological role of their residual plastid DNAs remains unclear.In this study,we obtained five bleached mutants by ofloxacin(Ofl)treatment,identified 12 residual plastid genes in five bleached mutants,and determined the mRNA levels in the wild type E.gracilis(WT)and one bleached mutant(OflB2)under dark and light stimulation conditions by quantitative reverse transcribed PCR(qRTPCR).Results show that the expression of all selected plastid genes in both WT and OflB2 mutant did not change significantly in darkness,while their responses to light stimulation were different.Under the light stimulation conditions,half of the genes did not change significantly,while most of the other genes were down-regulated in OflB2 mutant and up-regulated in WT.Therefore,the bleached mutant retains part of the plastid genome and the plastid relic is responsive to light.Our research will help to understand the functions of residual plastid DNA and evolution of chloroplasts.
基金Supported by Natural Science Foundation of Yunnan Province(2011FB049)National Natural Science Foundation of China(31260481,31460516)+2 种基金Fund of Yunnan Education Department(2013Y251)Fund of the Department of Life Science and Technology,Kunming University(GXKM201505)Talent Fund for PhD(YJL11015)
文摘Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragments of exogenous gene were integrated to construct lettuce plastid expression vector p Brpo AGFP,which harbored the expression cassette Prrn-gfp-aad A-Tpsb A. The results showed that the amplified flanking fragments were 1.2 and 1.1 kb in size. After sequencing,restriction digestion,ligation and transformation,lettuce plastid expression vector containing expression cassette Prrn-gfp-aad A-Tpsb A was constructed and confirmed by SDS-PAGE electrophoresis. The results of SDS-PAGE electrophoresis indicated that gfp gene was efficiently expressed under the regulation of plasmid specific promoter Prrn and terminator Tpsb A. GFP accounted for 45. 6% of total soluble proteins; inclusion bodies accounted for 47.5 % of bacterial proteins,which reached relatively high expression levels. The construction of lettuce plastid expression vector p Brpo A-GFP laid a solid foundation for establishment of subsequent lettuce plastid transformation system and genetic improvement of lettuce using various functional genes.
文摘The novelty and suitability of the mitochondrial gene CO1 in DNA barcoding as a reliable identification tool in animal species are undisputed. This is attributed to its standardized sequencing segment of the mitochondrial cytochrome c oxidase-1 gene (CO1) which has the necessary universality and variability making it a generally acceptable barcode region. CO1 is a haploid single locus that is uniparentally-inherited. Protein-coding regions are present in high-copy numbers making it an ideal barcode. The mitochondrial oxidase subunit I (COI) gene is a robust barcode with a suitable threshold for delineating animals and is not subject to drastic length variation, frequent mononucleotide repeats or microinversions. However, a low nucleotide substitution rate of plant mitochondrial genome [mtDNA] precludes the use of CO1 as a universal plant DNA barcode and makes the search for alternative barcode regions necessary. Currently, there exists no universal barcode for plants. The plastid region reveals leading candidate loci as appropriate DNA barcodes yet to be explored in biodiversity studies in Kenya. Four of these plastid regions are portions of coding genes (matK, rbcL, rpoB, and rpoC1), and three noncoding spacers (atpF-atpH, trnH-psbA, and psbK-psbL) which emerge as ideal candidate DNA loci. While different research groups propose various combinations of these loci, there exists no consensus;the lack thereof impedes progress in getting a suitable universal DNA barcode. Little research has attempted to investigate and document the applicability and extend of effectiveness of different DNA regions as barcodes to delineate cowpea at subspecies level. In this study we sought to test feasibility of the seven putative candidate DNA loci singly and in combination in order to establish a suitable single and multi-locus barcode regions that can have universal application in delineating diverse phylogeographic groups of closely related Kenyan cowpea variants. In this study, our focus was based on genetic parameters including analyses of intra- and infra-specific genetic divergence based on intra- and infra-specific K2P distances;calculation of Wilcoxon signed rank tests of intra-specific divergence among loci and coalescence analyses to delineate independent genetic clusters. Knowledge of DNA candidate loci that are informative will reveal the suitability of DNA barcoding as a tool in biodiversity studies. Results of this study indicate that: matK, trnH-psbA, psbK-psbL, and rbcL are good barcodes for delineating intra and infraspecific distances at single loci level. However, among the combinations, matK + trnH-psbA, rpoB + atpF-atpH + matK are the best barcodes in delineating cowpea subvariants. rbcL gene can be a suitable barcode marker at single locus level, but overall, multi locus approach appears more informative than single locus approach. The present study hopes to immensely contribute to the scanty body of knowledge on the novelty of DNA barcoding in cataloguing closely related cowpea variants at molecular level and hopes to open up future research on genomics and the possibility of use of conserved regions within DNA in inferring phylogenetic relationships among Kenyan cowpea variants.
基金supported by grants from the National Natural Science Foundation of China(32271912,32272634,32101484)。
文摘The expression of double-stranded RNAs(dsRNAs)from the plastid genome has been proven to be an effective method for controlling herbivorous pests by targeting essential insect genes.However,there are limitations to the efficiency of plastid-mediated RNA interference(PM-RNAi)due to the initial damage caused by the insects and their slow response to RNA interference.In this study,we developed transplastomic poplar plants that express dsRNAs targeting the b-Actin(dsACT)and Srp54k(dsSRP54K)genes of Plagiodera versicolora.Feeding experiments showed that transplastomic poplar plants can cause significantly higher mortality in P.versicolora larvae compared with nuclear transgenic or wild-type poplar plants.The efficient killing effect of PM-RNAi on P.versicolora larvae was found to be dependent on the presence of gut bacteria.Importantly,foliar application of a gut bacterial strain,Pseudomonas putida,will induce dysbiosis in the gut bacteria of P.versicolora larvae,leading to a significant acceleration in the speed of killing by PM-RNAi.Overall,our findings suggest that interfering with gut bacteria could be a promising strategy to enhance the effectiveness of PM-RNAi for insect pest control,offering a novel and effective approach for crop protection based on RNAi technology.
基金supported by the National Natural Science Foundation of China(32150710517)the Huazhong Agricultural University Scientific&Technological SelfInnovation Foundation(2016RC009)the National Key Research and Development Program of China,Ministry of Science and Education(2018YFD1000800).
文摘Mechanisms that allocate cellular space to organelles are of fundamental importance to biology but remain poorly understood.A detailed understanding of mechanisms that allocate cellular space to plastids,such as chloroplasts,will lead to high-yielding crops with enhanced nutritional value.The HIGH PIGMENT(HP)genes in tomato contribute to regulated proteolysis and abscisic acid metabolism.The HP1 gene was the first gene reported to influence the amount of cellular space occupied by chloroplasts and chromoplasts almost 20 years ago.Recently,our knowledge of mechanisms that allocate cellular space to plastids was enhanced by new information on the influence of cell type on the amount of cellular space occupied by plastids and the identification of new genes that help to allocate cellular space to plastids.These genes encode proteins with unknown and diverse biochemical functions.Several transcription factors were recently reported to regulate the numbers and sizes of chloroplasts in fleshy fruit.If these transcription factors do not induce compensating effects on cell size,they should affect the amount of cellular space occupied by plastids.Although we can now propose more detailed models for the network that allocates cellular space to plastids,many gaps remain in our knowledge of this network and the genes targeted by this network.Nonetheless,these recent breakthroughs provide optimism for future progress in this field.
基金supported by the National Natural Science Foundation of China(No.32370244)the Taishan Scholar Project(No.tsqn202306214)+1 种基金the Shandong Province Natural Science Foundation of China(No.ZR2023MC157)the State Key Laboratory of Pal-aeobiology and Stratigraphy(No.223123).
文摘The aquatic plant Nymphaea,a model genus of the early flowering plant lineage Nymphaeales and family Nymphaeaceae,has been extensively studied.However,the availability of chloroplast genome data for this genus is incomplete,and phylogenetic relationships within the order Nymphaeales remain controversial.In this study,12 chloroplast genomes of Nymphaea were assembled and analyzed for the first time.These genomes were 158,290-160,042 bp in size and contained 113 non-repeat genes,including 79 protein-coding genes,30 tRNA genes,and four rRNA genes.We also report on codon usage,RNA editing sites,microsatellite structures,and new repetitive sequences in this genus.Comparative genomics revealed that expansion and contraction of IR regions can lead to changes in the gene numbers.Additionally,it was observed that the highly variable regions of the chloroplast genome were mainly located in intergenic regions.Furthermore,the phylogenetic tree showed the order Nymphaeales was divided into three families,and the genus Nymphaea can be divided into five(or three)subgenera,with the subgenus Nymphaea being the oldest.The divergence times of nymphaealean taxa were analyzed,with origins of the order Nymphaeales and family Nymphaeaceae being about 194 and 131 million years,respectively.The results of the phylo-genetic analysis and estimated divergence times will be useful for future evolutionary studies of basal angiosperm lineages.
文摘Chloroplasts （plastids） possess a genome and their own machinery to express it. Translation in plastids occurs on bacterial-type 70S ribosomes utilizing a set of tRNAs that is entirely encoded in the plastid genome. In recent years, the components of the chloroplast translational apparatus have been intensely studied by proteomic approaches and by reverse genetics in the model systems tobacco （plastid-encoded components） and Arabidopsis （nucleus-encoded components）. This work has provided important new insights into the structure, function, and biogenesis of chloroplast ribosomes, and also has shed fresh light on the molecular mechanisms of the translation process in plastids. In addition, mutants affected in plastid translation have yielded strong genetic evidence for chloroplast genes and gene products influencing plant develop- ment at various levels, presumably via retrograde signaling pathway（s）. In this review, we describe recent progress with the functional analysis of components of the chloroplast translational machinery and discuss the currently available evidence that supports a significant impact of plastid translational activity on plant anatomy and morphology.
基金supported by grants from the National Natural Science Foundation of China(91935301)National Natural Science Foundation of China Joint Program(U1701232)+4 种基金Jiangsu Science and Technology Development Program(BE2021360)Jiangsu Agricultural Science and Technology Innovation Fund Project(SCX(19)1079)Jiangsu Province Agriculture Independent Innovation Fund Project(CX(19)1002)National Key Research and Development Program of China(2016YFD0100903)the Fundamental Research Funds for the Central Universities(JCQY201902).
文摘Plastid-to-nucleus retrograde signaling coordinates nuclear gene expression with chloroplast developmental status and is essential for the photoautotrophic lifestyle of plants.Previous studies have established that tetrapyrrole biosynthesis(TPB)and plastid gene expression(PGE)play essential roles in plastid retrograde signaling during early chloroplast biogenesis;however,their functional relationship remains unknown.In this study,we generated a series of rice TPB-related gun(genome uncoupled)mutants and systematically analyzed their effects on nuclear and plastid gene expression under normal conditions or when subjected to treatments with norflurazon(NF;a noncompetitive inhibitor of carotenoid biosynthesis)and/or lincomycin(Lin;a specific inhibitor of plastid translation).We show that under NF treatment,expression of plastid-encoded polymerase(PEP)-transcribed genes is significantly reduced in the wild type but is derepressed in the TPB-related gun mutants.We further demonstrate that the derepressed expression of PEPtranscribed genes may be caused by increased expression of the PEP core subunit and nuclear-encoded sigma factors and by elevated copy numbers of plastid genome per haploid genome.In addition,we show that expression of photosynthesis-associated nuclear genes(PhANGs)and PEP-transcribed genes is correlated in the rice TPB-related gun mutants,with or without NF or Lin treatment.A similar correlation between PhANGs and PGE is also observed in the Arabidopsis gun4 and gun5 mutants.Moreover,we show that increased expression of PEP-transcribed plastid genes is necessary for the gun phenotype in NF-treated TPB-related gun mutants.Further,we provide evidence that these TPB-related GUN genes act upstream of GUN1 in the regulation of retrograde signaling.Taken together,our results suggest that the TPB-related GUN genes control retrograde plastid signaling by regulating the PGE-dependent retrograde signaling pathway.
基金supported by the National Natural Science Foundation of China (NSFC)(31571464, 31371438, 31070222 to Quan-Sheng Qiu)the National Basic Research Program of China (973)project, 2013CB429904 to Quan-Sheng Qiu)+5 种基金the Research Fund for the Doctoral Program of Higher Education of China(RFDP)(20130211110001 to Quan-Sheng Qiu)Research Team of Stress Tolerance Mechanisms and Molecular Breeding of Plateau PlantsQinghai Province “Kunlun Talents·Advanced Innovative and Entrepreneurial Talents” Program (2022 to QuanSheng Qiu)the Qinghai Provincial Department of Science and Technology Qinghai basic research program (2022-ZJ-724 to Quan-Sheng Qiu)the Independent Research and Development Project of State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems (202202 to Quan-Sheng Qiu)the Core Facility of School of Life Sciences,Lanzhou University。
文摘Arabidopsis plastid antiporters KEA1 and KEA2are critical for plastid development, photosynthetic efficiency, and plant development.Here, we show that KEA1 and KEA2 are involved in vacuolar protein trafficking. Genetic analyses found that the kea1 kea2 mutants had short siliques, small seeds, and short seedlings. Molecular and biochemical assays showed that seed storage proteins were missorted out of the cell and the precursor proteins were accumulated in kea1 kea2. Protein storage vacuoles(PSVs) were smaller in kea1 kea2. Further analyses showed that endosomal trafficking in kea1 kea2 was compromised. Vacuolar sorting receptor 1(VSR1) subcellular localizations, VSR–cargo interactions, and p24 distribution on the endoplasmic reticulum(ER) and Golgi apparatus were affected in kea1 kea2. Moreover, plastid stromule growth was reduced and plastid association with the endomembrane compartments was disrupted in kea1 kea2. Stromule growth was regulated by the cellular pH and K+homeostasis maintained by KEA1 and KEA2. The organellar pH along the trafficking pathway was altered in kea1 kea2. Overall, KEA1 and KEA2 regulate vacuolar trafficking by controlling the function of plastid stromules via adjusting pH and K+homeostasis.
文摘Carotenoids are indispensable to plants and critical in human diets. Plastids are the organelles for carotenoid biosynthesis and storage in plant cells. They exist in various types, which include proplastids, etioplasts, chloroplasts, amyloplasts, and chromoplasts. These plastids have dramatic differences in their capacity to synthesize and sequester carotenoids. Clearly, plastids play a central role in governing carotenogenic activity, carotenoid stability, and pigment diversity. Understanding of carotenoid metabolism and accumulation in various plastids expands our view on the multifaceted regulation of carotenogenesis and facilitates our efforts toward developing nutrient-enriched food crops. In this review, we provide a comprehensive overview of the impact of various types of plastids on carotenoid biosynthesis and accumulation, and discuss recent advances in our understanding of the regulatory control of carotenogenesis and metabolic engineering of carotenoids in light of plastid types in plants.
基金ACKNOWLEDGMENTS We thank Joyce Bower and Dr David Yoder for generating the ftsZl-1 ftsZ2-2 double mutant and Mia Hemmes for assistance in the cloning of pBluescript P4-P1R and pBluescript P2R-P3. No conflict of interest declared.This work was supported by National Science Foundation grant 0544676 to K.W.O.
文摘FtsZ1 and FtsZ2 are phylogenetically distinct families of FtsZ in plants that co-localize to mid-plastid rings and facilitate division of chloroplasts. In plants, altered levels of either FtsZ1 or FtsZ2 cause dose-dependent defects in chloroplast division; thus, studies on the functional relationship between FtsZgenes require careful manipulation of FtsZ levels in vivo. To define the functional relationship between the two FtsZ2 genes in Arabidopsis thaliana, FtsZ2-1 and FtsZ2-2, we expressed FtsZ2-1 in an ftsZ2-2 null mutant, and vice versa, and determined whether the chloroplast division defects were rescued in plants expressing different total levels of FtsZ2. Full rescue was observed when either the FtsZ2-1 or FtsZ2-2 level approximated total FtsZ2 levels in wild-type （WT）. Additionally, FtsZ2-2 interacts with ARC6, as shown previously for FtsZ2- 1. These data indicate that FtsZ2-1 and FtsZ2-2 are functionally redundant for chloroplast division in Arabidopsis. To rigorously validate the requirement of each FtsZ family for chloroplast division, we replaced FtsZ1 with FtsZ2 in vivo, and vice versa, while maintaining the FtsZ level in the transgenic plants equal to that of the total level in WT. Chloroplast division defects were not rescued, demonstrating conclusively that FtsZ1 and FtsZ2 are non-redundant for maintenance of WT chloroplast numbers. Finally, we generated ftsZtriple null mutants and show that plants completely devoid of FtsZ protein are viable and fertile. As plastids are presumably essential organelles, these findings suggest that an FtsZ-independent mode of plastid partitioning may occur in higher plants.
基金This research was supported by National Science Foundation grants IBN-9808904 （M,R. and J.M.） and IOS-0726178 （M.R. and M.T.） the American Society of Plant Biologists＇ Education Foundation （M.R. and M.T.）+1 种基金 Ministry for Food, Agriculture, Forestry, and Fisheries, Korean Government, Korea Research Foundation （J.L.） the National Institutes of Health （grant R01ES013679 to D.B.）, and the University of Maine （M.R.）. This is Maine Agricultural and Forest Experiment Station Publication Number 3079, Hatch Project no. ME08361-08MRF （NC 1168）.ACKNOWLEDGMENTS The authors thank Dr Michael Salvucci for providing antibodies to PRK and Dr Jorn Petersen for analyzing the genomic PRK sequence for introns. No conflict of interest declared.
文摘Phosphoribulokinase （PRK）, a nuclear-encoded plastid-localized enzyme unique to the photosynthetic carbon reduction （Calvin） cycle, was cloned and characterized from the stramenopile alga Vaucheria litorea. This alga is the source of plastids for the mollusc （sea slug） Elysia chlorotica which enable the animal to survive for months solely by photoautotrophic CO2 fixation. The 1633-bp V. litorea prk gene was cloned and the coding region, found to be interrupted by four introns, encodes a 405-amino acid protein. This protein contains the typical bipartite target sequence expected of nuclearencoded proteins that are directed to complex （i.e. four membrane-bound） algal plastids. De novo synthesis of PRK and enzyme activity were detected in E. chlorotica in spite of having been starved of V. litorea for several months. Unlike the algal enzyme, PRK in the sea slug did not exhibit redox regulation. Two copies of partial PRK-encoding genes were isolated from both sea slug and aposymbiotic sea slug egg DNA using PCR. Each copy contains the nucleotide region spanning exon 1 and part of exon 2 of V litorea prk, including the bipartite targeting peptide. However, the larger prk fragment also includes intron 1. The exon and intron sequences of prk in E. chlorotica and V/itorea are nearly identical. These data suggest that PRK is differentially regulated in V. litorea and E. chlorotica and at least a portion of the V. litorea nuclear PRK gene is present in sea slugs that have been starved for several months.
